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https://www.readbyqxmd.com/read/28102957/rf-safety-assessment-of-a-bilateral-four-channel-transmit-receive-7-tesla-breast-coil-sar-versus-tissue-temperature-limits
#1
Thomas M Fiedler, Mark E Ladd, Andreas K Bitz
PURPOSE: The purpose of this work was to perform an RF safety evaluation for a bilateral four-channel transmit/receive breast coil and to determine the maximum permissible input power for which RF exposure of the subject stays within recommended limits. The safety evaluation was done based on SAR as well as on temperature simulations. In comparison to SAR, temperature is more directly correlated with tissue damage, which allows a more precise safety assessment. The temperature simulations were performed by applying three different blood perfusion models as well as two different ambient temperatures...
January 2017: Medical Physics
https://www.readbyqxmd.com/read/28102949/simultaneous-pet-mr-imaging-with-a-radio-frequency-penetrable-pet-insert
#2
Alexander M Grant, Brian J Lee, Chen-Ming Chang, Craig S Levin
PURPOSE: A brain sized radio frequency (RF)-penetrable PET insert has been designed for simultaneous operation with MRI systems. This system takes advantage of electro-optical coupling and battery power to electrically float the PET insert relative to the MRI ground, permitting RF signals to be transmitted through small gaps between the modules that form the PET ring. This design facilitates the use of the built-in body coil for RF transmission and thus could be inserted into any existing MR site wishing to achieve simultaneous PET/MR imaging...
January 2017: Medical Physics
https://www.readbyqxmd.com/read/28102930/modulation-of-the-thermodynamic-signatures-of-an-rna-thermometer-by-osmolytes-and-salts
#3
Mimi Gao, Loana Arns, Roland Winter
Folding of ribonucleic acids (RNAs) is driven by several factors, such as base pairing and stacking, chain entropy, and ion-mediated electrostatics, which have been studied in great detail. However, the power of background molecules in the cellular milieu is often neglected. Herein, we study the effect of common osmolytes on the folding equilibrium of a hairpin-structured RNA and, using pressure perturbation, provide novel thermodynamic and volumetric insights into the modulation mechanism. The presence of TMAO causes an increased thermal stability and a more positive volume change for the helix-to-coil transition, whereas urea destabilizes the hairpin and leads to an increased expansibility of the unfolded state...
January 19, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28102428/plasma-adamts13-activity-and-von-willebrand-factor-antigen-and-activity-in-patients-with-subarachnoid-haemorrhage
#4
Monisha Kumar, Wenjing Cao, Jenny K McDaniel, Huy P Pham, Dheeraj Raju, Kelsey Nawalinski, Suzanne Frangos, David Kung, Eric Zager, Scott E Kasner, Joshua M Levine, X Long Zheng
Increased von Willebrand factor (VWF) and reduced ADAMTS13 activity are associated with arterial thrombosis. This may also be the culprit mechanism implicated in delayed cerebral ischaemia after aneurysmal subarachnoid haemorrhage (SAH). It was our objective to determine plasma VWF and ADAMTS13 in patients with SAH and healthy subjects; and to explore the levels of those markers and outcome after SAH. Forty consecutive patients were enrolled between September 2007 and April 2014 in a pilot study. Plasma samples were collected from SAH patients on post-bleed day (PBD) 0, 1, 3, 5, 7 and 10 and healthy controls...
January 19, 2017: Thrombosis and Haemostasis
https://www.readbyqxmd.com/read/28102305/structure-and-membrane-interactions-of-the-homodimeric-antibiotic-peptide-homotarsinin
#5
Rodrigo M Verly, Jarbas M Resende, Eduardo F C Junior, Mariana T Q de Magalhães, Carlos F C R Guimarães, Victor H O Munhoz, Marcelo Porto Bemquerer, Fábio C L Almeida, Marcelo M Santoro, Dorila Piló-Veloso, Burkhard Bechinger
Antimicrobial peptides (AMPs) from amphibian skin are valuable template structures to find new treatments against bacterial infections. This work describes for the first time the structure and membrane interactions of a homodimeric AMP. Homotarsinin, which was found in Phyllomedusa tarsius anurans, consists of two identical cystine-linked polypeptide chains each of 24 amino acid residues. The high-resolution structures of the monomeric and dimeric peptides were determined in aqueous buffers. The dimer exhibits a tightly packed coiled coil three-dimensional structure, keeping the hydrophobic residues screened from the aqueous environment...
January 19, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28102013/the-effect-of-potassium-diclofenac-and-dexamethasone-on-mmp-1-gene-transcript-levels-during-experimental-tooth-movement-in-rats
#6
G P Molina Da Silva, O M Tanaka, D F Campos Navarro, C E Repeke, G P Garlet, O Guariza-Filho, P C Trevilatto
OBJECTIVES: The aim of this study was to analyze MMP-1 transcript levels in periodontal tissues of rats that underwent orthodontic treatment using potassium diclofenac and dexamethasone at different stages of tooth movement. SETTING AND SAMPLE POPULATION: The sample comprised of ninety male Wistar rats. MATERIAL AND METHODS: A closed nickel-titanium coil spring was used to apply a force of 50 cN to move the maxillary right first molars mesially...
February 2017: Orthodontics & Craniofacial Research
https://www.readbyqxmd.com/read/28101873/biomaterials-made-from-coiled-coil-peptides
#7
Vincent Conticello, Spencer Hughes, Charles Modlin
The development of biomaterials designed for specific applications is an important objective in personalized medicine. While the breadth and prominence of biomaterials have increased exponentially over the past decades, critical challenges remain to be addressed, particularly in the development of biomaterials that exhibit highly specific functions. These functional properties are often encoded within the molecular structure of the component molecules. Proteins, as a consequence of their structural specificity, represent useful substrates for the construction of functional biomaterials through rational design...
2017: Sub-cellular Biochemistry
https://www.readbyqxmd.com/read/28101868/dystrophin-and-spectrin-two-highly-dissimilar-sisters-of-the-same-family
#8
Olivier Delalande, Aleksander Czogalla, Jean-François Hubert, Aleksander Sikorski, Elisabeth Le Rumeur
Dystrophin and Spectrin are two proteins essential for the organization of the cytoskeleton and for the stabilization of membrane cells. The comparison of these two sister proteins, and with the dystrophin homologue utrophin, enables us to emphasise that, despite a similar topology with common subdomains and a common structural basis of a three-helix coiled-coil, they show a large range of dissimilarities in terms of genetics, cell expression and higher level structural organisation. Interactions with cellular partners, including proteins and membrane phospholipids, also show both strikingly similar and very different behaviours...
2017: Sub-cellular Biochemistry
https://www.readbyqxmd.com/read/28101867/myosin-and-actin-filaments-in-muscle-structures-and-interactions
#9
John M Squire, Danielle M Paul, Edward P Morris
In the last decade, improvements in electron microscopy and image processing have permitted significantly higher resolutions to be achieved (sometimes <1 nm) when studying isolated actin and myosin filaments. In the case of actin filaments the changing structure when troponin binds calcium ions can be followed using electron microscopy and single particle analysis to reveal what happens on each of the seven non-equivalent pseudo-repeats of the tropomyosin α-helical coiled-coil. In the case of the known family of myosin filaments not only are the myosin head arrangements under relaxing conditions being defined, but the latest analysis, also using single particle methods, is starting to reveal the way that the α-helical coiled-coil myosin rods are packed to give the filament backbones...
2017: Sub-cellular Biochemistry
https://www.readbyqxmd.com/read/28101865/tropomyosin-structure-function-and-interactions-a-dynamic-regulator
#10
Sarah E Hitchcock-DeGregori, Bipasha Barua
Tropomyosin is the archetypal-coiled coil, yet studies of its structure and function have proven it to be a dynamic regulator of actin filament function in muscle and non-muscle cells. Here we review aspects of its structure that deviate from canonical leucine zipper coiled coils that allow tropomyosin to bind to actin, regulate myosin, and interact directly and indirectly with actin-binding proteins. Four genes encode tropomyosins in vertebrates, with additional diversity that results from alternate promoters and alternatively spliced exons...
2017: Sub-cellular Biochemistry
https://www.readbyqxmd.com/read/28101862/crystallographic-studies-of-intermediate-filament-proteins
#11
Dmytro Guzenko, Anastasia A Chernyatina, Sergei V Strelkov
Intermediate filaments (IFs), together with microtubules and actin microfilaments, are the three main cytoskeletal components in metazoan cells. IFs are formed by a distinct protein family, which is made up of 70 members in humans. Most IF proteins are tissue- or organelle-specific, which includes lamins, the IF proteins of the nucleus. The building block of IFs is an elongated dimer, which consists of a central α-helical 'rod' domain flanked by flexible N- and C-terminal domains. The conserved rod domain is the 'signature feature' of the IF family...
2017: Sub-cellular Biochemistry
https://www.readbyqxmd.com/read/28101860/the-structure-and-topology-of-%C3%AE-helical-coiled-coils
#12
Andrei N Lupas, Jens Bassler, Stanislaw Dunin-Horkawicz
α-Helical coiled coils constitute one of the most diverse folds yet described. They range in length over two orders of magnitude; they form rods, segmented ropes, barrels, funnels, sheets, spirals, and rings, which encompass anywhere from two to more than 20 helices in parallel or antiparallel orientation; they assume different helix crossing angles, degrees of supercoiling, and packing geometries. This structural diversity supports a wide range of biological functions, allowing them to form mechanically rigid structures, provide levers for molecular motors, project domains across large distances, mediate oligomerization, transduce conformational changes and facilitate the transport of other molecules...
2017: Sub-cellular Biochemistry
https://www.readbyqxmd.com/read/28101859/functional-and-structural-roles-of-coiled-coils
#13
Marcus D Hartmann
Coiled coils appear in countless structural contexts, as appendages to small proteins, as parts of multi-domain proteins, and as building blocks of filaments. Although their structure is unpretentious and their basic properties are understood in great detail, the spectrum of functional properties they provide in different proteins has become increasingly complex. This chapter aims to depict this functional spectrum, to identify common themes and their molecular basis, with an emphasis on new insights gained into dynamic aspects...
2017: Sub-cellular Biochemistry
https://www.readbyqxmd.com/read/28101858/coiled-coil-design-updated-and-upgraded
#14
Derek N Woolfson
α-Helical coiled coils are ubiquitous protein-folding and protein-interaction domains in which two or more α-helical chains come together to form bundles. Through a combination of bioinformatics analysis of many thousands of natural coiled-coil sequences and structures, plus empirical protein engineering and design studies, there is now a deep understanding of the sequence-to-structure relationships for this class of protein architecture. This has led to considerable success in rational design and what might be termed in biro de novo design of simple coiled coils, which include homo- and hetero-meric parallel dimers, trimers and tetramers...
2017: Sub-cellular Biochemistry
https://www.readbyqxmd.com/read/28101207/structure-function-analysis-of-dna-helicase-helq-a-new-diagnostic-marker-in-ovarian-cancer
#15
Ya-Ping Li, Jun-Juan Yang, Hui Xu, En-Yu Guo, Yan Yu
It has been previously reported that a deficiency of the helicase, POLQ-like (HELQ) gene increases the risk of ovarian cancer. The present study aimed to explore the structure-function association of HELQ and discuss the effect of molecular structure on the occurrence of tumors. ExPASy tools were employed to analyze the physicochemical properties and secondary structure of the genes. PHYRE2 Protein Fold Recognition Server was used to construct the three-dimensional model and find the ligand-binding sites of HELQ...
December 2016: Oncology Letters
https://www.readbyqxmd.com/read/28100993/cdc-group-eo-4-and-candida-tropicalis-peritonitis-in-a-patient-on-peritoneal-dialysis-after-upper-endoscopy-colonoscopy-and-coil-embolization-of-the-gastroduodenal-artery
#16
Shameek Gayen, Yonah Ziemba, Shikha Jaiswal, Adam Frank, Yasmin Brahmbhatt
Peritoneal dialysis (PD) is an excellent form of renal replacement therapy for many patients with end-stage renal disease (ESRD). Over 10,000 patients receive PD in the United States [United States Renal Data System: 2015 USRDS Annual Data Report: Epidemiology of Kidney Disease in the United States, 2015]. PD has superior outcomes compared to hemodialysis in the first 2 years of ESRD [Sinnakirouchenan and Holley: Adv Chronic Kidney Dis 2011;18: 428-432]. However, peritonitis is a known complication and may result in significant morbidity and necessitate transition to hemodialysis, which increases medical costs [Holley and Piraino: Semin Dial 1990;3: 245-248]...
September 2016: Case Reports in Gastroenterology
https://www.readbyqxmd.com/read/28100857/-clinical-features-and-findings-in-patients-with-unruptured-intracranial-aneurysms-aged-%C3%A2-80-years
#17
Tetsuhiro Kamo, Naoki Akioka, Daina Kashiwazaki, Masaki Koh, Naoya Kuwayama, Satoshi Kuroda
OBJECTIVE: It is difficult to decide whether to treat unruptured intracranial aneurysm(UIA)in elderly patients aged ≥80 years because they have potentially shorter life expectancy and risks related to treatment. Here, we report the results of the treatment of patients aged ≥80 years. METHODS: A retrospective review was performed in patients who underwent surgical or endovascular treatment between April 2012 and December 2015 at our institution. RESULTS: Between April 2012 and December 2015 we treated 130 UIA patients who presented with 145 aneurysms and 12 patients who presented with 14 aneurysms, who were aged ≥80 years...
January 2017: No Shinkei Geka. Neurological Surgery
https://www.readbyqxmd.com/read/28100156/transcatheter-embolization-of-type-i-endoleaks-associated-with-endovascular-abdominal-aortic-aneurysm-repair-using-ethylene-vinyl-alcohol-copolymer
#18
Assaf Graif, Ansar Z Vance, Mark J Garcia, Kevin T Lie, Michael K McGarry, Daniel A Leung
PURPOSE: To evaluate the feasibility, safety, and outcome of transcatheter embolization using ethylene vinyl alcohol copolymer (EVOH) of type I endoleaks associated with endovascular abdominal aortic aneurysm repair. PATIENT POPULATION AND METHODS: Retrospective chart review was performed to identify 8 consecutive patients who had undergone EVOH embolization for type I endoleaks between 2012 and 2015. The primary approach used to access the endoleak was the perigraft technique, where the endoleak itself is catheterized at the anastomotic site...
January 2017: Vascular and Endovascular Surgery
https://www.readbyqxmd.com/read/28100155/management-of-type-ii-endoleak-from-internal-iliac-artery-immediately-after-endovascular-aneurysm-repair
#19
Ming-Yi Hsu, Ta-Wei Su, I-Hao Su, Po-Jen Ko, Sung-Yu Chu
Inadvertent coverage of origin of internal iliac artery (IIA) during endovascular aneurysm repair may lead to type II endoleak. Except for open surgery, the endovascular solution is limited. We report a case with such complication that was successfully treated with coil embolization using retrograde extrastent approach. This is a new technique that has not been reported before, and as such, had been useful in the treatment of type II endoleak from IIA as an alternative to open ligation of IIA origin.
January 2017: Vascular and Endovascular Surgery
https://www.readbyqxmd.com/read/28096250/clinical-management-of-unruptured-intracranial-aneurysm-in-germany-a-nationwide-observational-study-over-a-5-year-period-2005-2009
#20
Victor Walendy, Andreas Stang
OBJECTIVES: Our aim was to provide nationwide age-standardised rates (ASR) on the usage of endovascular coiling and neurosurgical clipping for unruptured intracranial aneurysm (UIA) treatment in Germany. SETTING: Nationwide observational study using the Diagnosis-Related-Groups (DRG) statistics for the years 2005-2009 (overall 83 million hospitalisations). PARTICIPANTS: From 2005 to 2009, overall 39 155 hospitalisations with a diagnosis of UIA occurred in Germany...
January 17, 2017: BMJ Open
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